This application claims the priorities of German Patent Application Serial No. 199 07 482.8, filed Feb. 11, 1999, and German Patent Application Serial No. 100 06 771.9, filed Feb. 10, 2000, the subject matter of which is incorporated herein by reference.
The invention relates to a vessel for metallurgical purposes for the transport of molten metals, and more particularly to a vessel that has a metal jacket with a heat-proof lining and opposing lifting lugs on the outside of the vessel, wherein the lifting lugs are supported by a lug shield connected to the metal jacket. The metal jacket can also have two axially spaced reinforcement rings, with the lifting lugs being supported by a lug shield which is connected with the reinforcement rings and forms a small radial gap to the metal jacket.
Vessels for metallurgical purposes are well known (see, for example, DE-AS 11 66 980, DE-PS 11 72 404, DE-AS 29 01 011). All designs have in common that the vessel has a metal jacket provided with heat-proof lining. Two opposing lifting lugs are disposed on the outside of the metal jacket, which are supported on a reinforcement strip, a lug shield or a box construction, all of which are in turn fixedly connected with the metal jacket. Typically, the metal jacket is reinforced with two circumferential reinforcement rings which are spaced apart in the axial direction, with the lug shield secured between the reinforcement rings. The known constructions are not optimized for stress and have a particularly unfavorable ratio of tare weight to filling weight.
An improved vessel for metallurgical purposes is known from DE 197 06 056 C1. It consists of a metal jacket provided with a heat-proof lining, is made of tubular sections of pipe and has two peripheral spaced-apart reinforcement rings which are integrated in the metal jacket. Two opposing lifting lugs are disposed on the outside of the metal jacket and supported by a respective lug shield which is connected with the reinforcement ring by a weld seam. The lug shield is disposed between the two reinforcement rings so as to have a small radial separation from the metal jacket.
Disadvantageously, the fixed connection between the lug shield and the reinforcement rings employed in this design generates high stress values as well as stress peaks in the connecting region which can reduce the total load capacity. Occasionally, additional stress reserves may not be available, thereby creating the risk of plastic flow.
It would therefore be desirable to provide a vessel for metallurgical purposes with a capacity between 80 tons and 400 tons, in particular a vessel with a circular cross-section, which has an improved stress distribution for the total load capacity in the region of the attachment of the lug shield, and which has increased stress reserves for preventing plastic deformation. Moreover, it would also be desirable to improve the ratio between tare weight and filling weight.
According to one aspect of the invention, the vessel has a metal jacket with a heat-proof lining and two opposing lifting lugs disposed on the outside of the vessel, wherein each of the lifting lugs is supported by a lug shield connected to the metal jacket. The lug shields allows limited movement in the vertical and peripheral direction. The metal jacket includes means for supporting the own weight of the lug shield and the vessel when the vessel is in a vertical or tilted position.
According to another aspect of the invention, the metal jacket can be made of sections of pipe and include two axially spaced-apart reinforcement rings integrated in the metal jacket. In this embodiment, the lug shield connected with the reinforcement rings instead of directly to the vessel.
With this arrangement, the relatively cold lug shield does not hinder the thermal expansion of the vessel, while forces can still be transmitted via these means. For example, the means can be formed as a box construction encircling the lug shield and allowing limited movement of the lug shield. It is immaterial if the box construction is rectangular, round or oval. When the vessel is in its rest position, the lug shield, due to its own weight, contacts the region of the box construction in the 6 o""clock position. When the vessel is lifted, the lug shield contacts the region of the box construction in the 12 o""clock position. For example, if the vessel is tilted by 90xc2x0, then the lug shield contacts the region of the box construction in the 3 o""clock or 9 o""clock position. Alternatively, the box construction can be replaced by clamp-like elements which frame the marginal regions of the lug shield. A free lug shield is optimal for stress management, because the vessel can unimpededly and freely expand in the vertical and circumferential direction when heating up. A different more advantageous arrangement of the lug shield may be selected depending on the size and the cross-section of the vessel. The forces to be transmitted have to be taken into account. In such design, only a marginal region of the lug shield facing the respective reinforcement ring is materially connected with the reinforcement ring. This design has the advantage that the material connection can transmit large forces, while allowing unrestricted expansion in the vertical direction, because the opposing marginal region can move freely. Depending on the design, the material connection can be strong enough so that means for supporting the tare weight, in particular in a tilted position of the vessel, can be eliminated. In other situations, a guide for guiding the freely moveable marginal region can be provided.
The means can be ribs which are guided in slots or guide tangs, with the marginal region of the lug shield guided in their respective gap, or clamps which guide the lateral regions of the freely moveable marginal region of the lug shield. The means can be integral parts of the reinforcement ring or can be connected with the reinforcement ring through a weld seam.
The material connection between the lug shield and the reinforcement ring is preferably provided on the upper reinforcement ring. To make the seam as short as possible, it is proposed to form this marginal region as a segment of the reinforcement ring, with the segment being materially connected to the abutting segments of the reinforcement ring by a transverse seam. The total length of the transverse seam is shorter than the peripheral longitudinal seam.
To simplify the construction further, the lower reinforcement ring can be omitted. In this modification, too, the marginal region of the lug shield can be guided or entirely omitted. The guide means are formed in a similar manner as in the aforedescribed construction of the vessel. A particular feature is a circumferential ring which is materially connected with the marginal region of the two lug shields. To provide sufficient guidance between the ring and the metal jacket, circumferentially distributed spacers are arranged on the lug shield and/or on the ring.
Further features and advantages of the present invention will be apparent from the following description of preferred embodiments and from the claims.